I only had one exposed beam to deal with. It was left covered up by the insulation guys that did the spray foam. They cover everything with plastic for good reason, and I had them leave most of it to protect stuff from drywall, mud, and later paint. All windows were masked off inside to the drywall. Any vents too. Then I had bought a commercial Graco sprayer (low end for commercial stuff but plenty good for me) and sprayed primer all over everything. Super easy to do Then I cam e back over it and sprayed the color coat on all the walls and didn't worry about hitting the ceiling. I found I had to back-roll to get good even coverage but that was still pretty fast with a friend helping. Finally I masked off the walls at the ceiling and sprayed the ceilings (knock down texture on them). Then pulled plastic from everything and was mostly done. The exceptions were rooms that got different wall colors which were done individually with roller and brush, but the ceilings were all shot with the gun first for those.
BUT... You will spend a lot of time covering everything first. But once you start spraying, it goes fast and covers very nicely. You will absolutely have to wear a respirator when doing this as it is nearly impossible to vent the place with all the windows and doors masked over and besides you will be in a fog of paint the whole time, even if you can vent the place.
